What does this horrific worst nightmare i ever had mean?

[Cosine]

Ok, so like a week ago i had this nightmare and this guy who is my friend in real life who is in my dreams quite often was in this one.... lets just call him Jackson. So I was playing basketball with a girl who was my friend. For some stupid reason i attached a spear to the ball so it would go in the basket more accurately. So i tried shooting, and i missed and jackson was walking by and the spear went right through his heart and came out his back. I screamed and he tore out the spear and i remember yelling "You are going to bleed 2 death!" and i was crying.. i never had a nightmare like it before.....it was quite vivid. please tell me what my nightmare means